Drafting mechanism



Sept. 6, 1960 v U H M 2,951,236

DRAFTING MECHANISM Filed Jan. 30, 1956 United Stats atent O 7 2,951,266 DRAFTING MECHANISM Virgil A. Burnham, Saco, Maine, assignor to Saco-Lowell Shops, Boston, Mass., a corporation of Maine Filed Jan. 30, 1956, Ser. No. 562,211

6 Claims. (Cl. 19-131) This invention relates to textile fiber drafting mechamisms for spinning and roving frames or the like, and

more particularly, to novel drafting element arrangements including magnetic weighting thereof.

It has been known to be desirable from the standpoint of yarn quality to employ as the bottom roll, as well as the top roll, of a conventional pair of drafting rolls, a roll having a resilient covering applied either directly to the roll, or with bottom rolls particularly in the more usual form of an endless apron. Although the former system isthe more preferable one for many uses, it is generally considered to be impractical for bottom rolls due to the length of the usual bottom roll and the alinement and maintenance difiiculties which result from an arrangement having 40' or 50 resilient bosses mounted on a single long roll more or less permanently mounted in the machine and driven from its end by the usual gearing. Hence, the use of aprons about the bottom roll is more generally resorted to, since such aprons are less critical of installation than are bosses, and may be separately tensioned as by apron bars or tension pulleys.

The general arrangement of Burnham et a1. Patent No. 2,689,383, wherein a top weighted three-roll stack is employed with the long roll driving from beneath a series of shorter bottom drafting rolls which in turn drive overlying drafting rolls, although possibly an acceptable solution to the problem since it enables the short bottom drafting rolls to be quickly and easily replaced, has been found to have certain problems which arise when the overlying roll nipst'he apron, the result being that the apron tends to bulge away from the roll and drafting hence becomes erratic. Furthermore, sudh structure is somewhat complicated particularly as to its necessary weighting and roll supporting arrangements, and such complication tends to limit its use to applications in which advantage may be taken of the ability of such apparatus to handle mixtures of various kinds of fibers, for example.

According to the present invention, novel drafting element arrangements of the three-roll stack type are provided wherein a short magnetic roll is employed as the bottom drafting roll positioned between the long lowermost steel driving roll and the overlying top roll. Suc h arrangement makes possible not only the practical use of bottom drafting rolls having integral resilient coverings applied directly thereto so that the overlying roll and bottom drafting roll may nip the fiber there- 'between, but it also eliminates to a large degree the conventional roll supporting and weighting mechanism. Preferably, the bottom drafting rolls of the present invention are of the resilient two-boss type resting on and frictiona1ly driven by a long lowermost steel roll and in turn driving a resilient two-boss overlying control roll reststack, supplies the entire weighting pressure by pressing both the overlying roll with its apron cradle if one be used and the driving roll into firm pressure contact with it, although a magnetic overlying roll could be used if higher weighting pressure is desired than can be supplied by the magnetic bottom drafting roll alone. A suitable mounting, such as cap bars, is provided to allow limited movement of the rolls toward and away from one another. The front and rear pairs of rolls, where used, preferably comprise a steel lower roll and a resilient magnetic overlying roll as shown in my Patent No. 2,686,940, although a three-roll stack arrangement of the present invention may be substituted for either or both if required.

'For the purpose of more fully describing further objects and features of my invention, reference is now made to the following specification and the appended drawings disclosing my presently preferred embodiment of the invention wherein:

Fig. l is a side cross-sectional elevational view of the apparatus of the invention, and

Fig. 2 is an end cross-sectional elevational view of the apparatus of Fig. 1 taken on the line 2-2 thereof.

Referring to the drawings, the textile fiber drafting mechanism of the invention includes a pair of delivery rolls 2 and 4 at its front end and a pair of holding Preferably, too, the magnetic rolls 6 and 8 at its back end forming between said pairs a drafting zone. The lower delivery roll 2 and the lower holding roll 6 extend for substantially the entire length of the machine and are driven in the customary manner by gears located at the end of the spin ning or roving frame. The upper delivery rolls 4 and the upper holding rolls 8 are supported and weighted by suitable means to act on a sliver to feed and draft it, the arrangement herein shown being that of Burnham US. Patent No. 2,686,940. Such arrangement includes a long lowermost driven roll of ferrous material mounted in suitable bearings in the spinning or roving frame and a series of short upper rolls mounted in cap bar slots 10 on said frame above said lower rolls, the upper rolls 4, 8 being magnetic rolls of the type shown and described in my said Patent 2,686,940 cooperating with the ferrous lower rolls 2, 6 to press the rolls into contact with one another to provide the requisite weight for firmly gripping strands of fibers passing between the rolls. order to maintain a firm pressure on the sliver at each of the pairs of rolls, the lower rolls 2 and 6 may be finely fluted and the upper rolls 4 and 8 are provided with bosses 12 of resilient material, such as synthetic rubber of sufiicient firmness to cooperate with the lower rolls to produce a continuously uniform bite or nip, but still having suificient softness and elasticity to conform to variations in cross sectional shape of the sliver being fed between them.

According to the present invention, a three-roll stack is provided as the rotary fiber control element of the described arrangement, although such three-roll stack could be provided for other purposes, such as the front rolls if desired. Such three-roll stack includes a long lowermost steel driving roll 14 which extends for substantially the entire length of the machine and is mounted in suitable bearings therein, said roll being driven in the customary manner by gearing located at the end thereof. A short bottom drafting or control roll generally designated 16 is mounted above said long lowermost driving roll by its gudgeons 18 in eap bar slots 20 for movement toward and away from driving roll 14. The bottom drafting roll 16 ispreferably provided with a pair of resilient bosses 22 as hereinbefore described positioned adjacent the ends thereof to run in frictional driving contact with the long lowermost driving roll 14, although an apron could be 3 used under some circumstances to provide the resilient surface. The lowermost driving roll 14 may be provided with fluted portions to cooperate with said bosses to aid in driving bottom drafting roll 16 if desired. Cooperating with the bottom drafting roll 16 is an overlying drafting or control roll 24- herein shown as provided with a pair of resilient aprons 26 to aid in controlling the fibers passing between the control rolls. Such overlying roll is mounted in cap bar slots 23 by its gudgeons 30 for movement toward and away from bottom drafting roll 16 so that its aprons 26 will run in contact with the resilient bosses 22 on said bottom drafting roll. An overlying apron bar 32 mounted in suitable upper apron cradle side members 33 on overlying roll 24 is provided for tensioning the forward end of aprons 26 so that an extended fiber control zone over the top of bottom drafting control roll 16 is provided, such zone extending closely toward the nip of the delivery rolls 2, 4 to aid in controlling the drafting of fibers passing therethrough. As is best shown in Fig. 2, reduced portions are provided at the ends of control roll 24 for restraining the cradle assembly against axial movement, the cradle side members 33 being positioned against the shoulders of said reduced portions with their downwardly extending portions encircling same. This maintains the cradle assembly in position on roll 24 so that said roll and the portion of the periphery of the bottom roll 22 guiding the apron provide the sole support for the cradle assembly.

In order to weight the overlying roll 24 to provide suitable drafting pressure between it and the bottom drafting roll 16 and also to provide suitable driving pressure between bottom drafting roll 16 and its long lowermost driving roll 14, the middle roll of the three-roll stack, that is, bottom drafting roll 16, is a magnetic roll, the long lowermost driving roll 14, and the overlying drafting roll 24 being of ferrous material to cooperate therewith to provide a suitable magnetic flux path to press the three rolls together. It is also desirable to apply some weight to the overlying apron bar 32 to hold it in predetermined relationship to bottom drafting roll 16. Preferably, then, bar 32 is made of ferrous material so that it also may be magnetically weighted. Similarly, a cage or other holding means for the bar 32 can be magnetically weighted if made of ferrous material. Such expedients make more effective the support of the cradle assembly solely by the top roll 24 and the bottom roll 22.

More specifically, the bottom drafting roll 16 has a tubular sleeve 34 with reduced ends on which each boss 22 is mounted to provide a replaceable unit which is normally held on the roll by a collar 36. A magnet 38 is mounted centrally of said roll 16 within said sleeve 34 and pole pieces 49 are positioned at the ends of said magnet within the ends of said sleeve 34 and the collars 36, said collars preferably being screw threaded on said pole pieces for ready replacement of the bosses 2. The magnet itself is preferably of the permanent alloy type of magnet such as the well-known Alnico magnets.

In the arrangement shown, the top and bottom rolls act on two strands, said strands being fed between the bosses 22 of bottom roll 16 and their cooperating aprons 26 to draft and control them. Except for self weighting effects, the pressure with which these two strands are held is produced entirely by the magnetic flux created by the magnet 38, since the magnetic flux lines of a magnet tend to contract to pull the overlying roll 24 and the lowermost driving roll 14 into contact with the magnetic roll 16 positioned therebetween. However, since the lowermost driving roll 14 is fixed in the machine frame by its bearings, the resultant force tends to pull both magnetic bottom drafting roll 16 and overlying roll 24 downwardly into firm pressure contact with one another to provide the necessary driving friction between bottom drafting roll 16 and lowermost driving roll 14 and the necessary weighting pressure between overlying roll 24 and bottom drafting roll 16, as well as between apron bar 32 and the latter roll.

With the above described arrangement, the lower delivery, holding and driving rolls 2, 6 and 14 respectively, are rotated at the usual speeds to draft a strand, the weighting being provided entirely by the magnetic means above described. This not only provides an important simplification of the drafting element structure, but makes practical the employment of a lower drafting roll having integral or other resilient covering or surface which may be employed in conjunction with an overlying roll, having either a resilient covering or an apron, as shown, so that the fiber may be fed between the nip of two rolls having resilient surfaces. An apron may be also used with the lower drafting roll 16 to provide a resilient surface, al-

though for many uses, resilient bosses are preferable since by their use the problems of apron bulging are largely eliminated.

Thus it will be seen that I have provided a novel drafting element arrangement for spinning and roving frames whereby a three-roll stack makes possible the use of a pair of drafting rolls having resilient surfaces running in contact with one another for feeding a strand of fibers therebetween. Various modifications within the spirit of my invention and the scope of the invention will appear to those skilled in the art.

I claim:

1. A textile drafting mechanism including a three-roll stack having a lower driven ferrous roll, a bottom drafting roll driven therefrom and resting thereon, an overlying ferrous roll driven from said bottom drafting roll and resting thereon, mounting means locating said top and bottom drafting rolls in relation to each other and to said lower driven ferrous roll, an endless apron surrounding said top drafting roll and extending forwardly therefrom around a portion of the periphery of said bottom drafting roll, and cradle means located and supported solely by said top drafting roll and said portion of said periphery of said bottom drafting roll for guiding said apron, said bottom drafting roll including magnetic weighting means urging said bottom drafting roll against said driven roll and said overlying drafting roll toward said bottom drafting roll to press said apron into contact therewith.

2. A textile drafting mechanism including a three-roll stack having a lower driven ferrous roll, a bottom drafting roll driven therefrom and resting thereon, an overlying ferrous roll driven from said bottom drafting roll and resting thereon, mounting means locating said top and bottom drafting rolls in relation to each other and to said lower driven ferrous roll, an endless apron surrounding said top drafting roll and extending forwardly therefrom around a portion of the periphery of said bottom drafting roll, and cradle means including a ferrous apron bar positioned forwardly of said overlying roll with said bar within the loop of said apron at the forward portion thereof and in contact with said bottom drafting roll through said apron, said bottom drafting roll including magnetic weighting means urging said bottom drafting roll against said driven roll and said overlying drafting roll and said apron bar toward said bottom drafting roll to press said apron into contact therewith.

3. A textile drafting mechanism including a three-roll stack having a lower driven ferrous roll, a resilient surfaced bottom drafting roll driven therefrom and resting thereon, an overlying ferrous roll driven from said bottom drafting roll and resting thereon, mounting means locating said top and bottom drafting rolls in relation to each other and to said lower driven ferrous roll, an endless apron surrounding said top drafting roll and extending forwardly therefrom around a portion of the periphery of said bottom drafting roll, and cradle means including a ferrous apron bar positioned forwardly of said overlying roll with said bar within the loop of said apron at the forward portion thereof and in contact with said bottom drafting roll through said apron, said cradle means being located and supported solely by said top drafting roll and said portion of said periphery of said bottom drafting roll for guiding said apron, said bottom drafting roll including magnetic weighting means urging said bottom drafting roll against said driven roll and said overlying drafting roll and said apron bar toward said bottom drafting roll to press said apron into contact therewith.

4. A textile drafting mechanism including a three-roll stack having a lower driven ferrous roll, a bottom drafting roll driven therefrom and resting thereon, an overlying ferrous roll driven from said bottom drafting roll and resting thereon, mounting means locating said top and bottom drafting rolls in relation to each other and to said lower driven ferrous roll, an endless apron surrounding said top drafting roll and extending forwardly therefrom around a portion of the periphery of said bottom drafting roll, and cradle means including an apron bar positioned forwardly of said overlying roll with said bar within the loop of said apron at the forward portion thereof and in contact with said bottom drafting roll through said apron, said bottom drafting roll including magnetic weighting means urging said bottom drafting roll against said driven roll and said overlying drafting roll and said apron bar toward said bottom drafting roll to press said apron into contact therewith.

5. A textile drafting mechanism including a three-roll stack having a lower driven ferrous roll, a bottom drafting roll driven therefrom and resting thereon, an overlying ferrous roll driven from said bottom drafting roll and resting thereon, mounting means locating said top and bottom drafting rolls in relation to each other and to said lower driven ferrous roll, an endless apron surrounding said top drafting roll and extending forwardly therefrom around a portion of the periphery of said bottom drafting roll, and cradle means including an apron bar positioned forwardly of said overlying roll with said bar within the loop of said apron at the forward portion thereof and in contact with said bottom drafting roll through said apron, one of said rolls including magnetic weighting means urging said bottom drafting roll against said driven roll and said overlying drafting roll and said apron bar toward said bottom drafting roll to press said apron into contact therewith.

6. A magnetically weighted textile drafting mechanism including a bottom drafting roll, an overlying roll driven from said bottom drafting roll and resting thereon, mounting means locating said top and bottom drafting rolls in relation to each other, an endless apron surrounding said top drafting roll and extending forwardly therefrom around a portion of the periphery of said bottom drafting roll, and cradle means including an apron bar positioned forwardly of said overlying roll with said bar within the loop of said apron at the forward portion thereof and in contact with said bottom drafting roll through said apron, and cradle means located and supported solely by said top drafting roll and said portion of the periphery of said bottom drafting roll guiding said apron, one of said rolls including magnetic weighting means urging said overlying drafting roll and said apron bar toward said bottom drafting roll to press said apron into contact therewith.

References Cited in the file of this patent UNITED STATES PATENTS 1,254,390 Casablancas Ian. 22, 1918 2,178,627 Devaux Nov. 7, 1939 2,686,940 Burnham Aug. 24, 1954 2,751,631 Hunter et a1 June 26, 1956 

